1. Field of the Invention
The present invention relates to charging control for a communication connection in case of a relocation of a charging functionality. In particular, the present invention relates to a mechanism for charging control, such as online charging and/or pre-paid based charging, in a communication network where at least a part of charging functions is affected by mobility of a mobile station and the change of network elements caused thereby.
2. Related Prior Art
In the last years, an increasing extension of communication networks, e.g. of wire based communication networks, such as the Integrated Services Digital Network (ISDN), or wireless communication networks, such as the cdma2000 (code division multiple access) system, cellular 3rd generation (3G) communication networks like the Universal Mobile Telecommunications System (UMTS), cellular 2nd generation (2G) communication networks like the Global System for Mobile communications (GSM), the General Packet Radio System (GPRS), the Enhanced Data Rates for Global Evolutions (EDGE), or other wireless communication system, such as the Wireless Local Area Network (WLAN) or Worldwide Interoperability for Microwave Access (WiMax), took place all over the world. Various organizations, such as the 3rd Generation Partnership Project (3GPP), Telecoms & Internet converged Services & Protocols for Advanced Networks (TISPAN), the International Telecommunication Union (ITU), 3rd Generation Partnership Project 2 (3GPP2), Internet Engineering Task Force (IETF), the IEEE (Institute of Electrical and Electronics Engineers), the WiMAX Forum and the like are working on standards for telecommunication network and access environments.
In order to gain access to network and service resources, it is necessary that a subscriber performs an authentication and authorization procedure, also known as Authentication-Authorization-Accounting (AAA). For an AAA signaling, an AAA protocol may be used, such as RADIUS (Remote Authentication Dial-In User Service) or Diameter, between concerned network elements or nodes, such as between a local network AAA (client) node (responsible for service authentication if this is provided in the local network) and a home network that holds the subscription data and/or a home AAA server.
Authentication refers to the confirmation that the subscriber who is requesting services is a valid user of the network services requested. For this purpose, an identity and credentials are used. Authorization describes the grant of services to the requesting subscriber on the basis of the service request and the authentication result. Accounting, on the other hand, is related to the tracking of the consumption of resources and is used for management, billing, charging and the like. With regard to charging, currently two modes are normally used, i.e. online charging and offline charging.
As an example for a charging scheme to be used in a communication network, a Diameter Credit Control Application (DCCA) is designed by IETF and then enriched by 3GPP to be used as the control protocol for online charging. DCCA is based on client (such as a charging or prepaid client (PPC))/server (charging or prepaid server (PPS)) mode. In FIG. 9, a known example of a configuration of a corresponding charging system and network elements involved thereby is shown.
In FIG. 9, reference sign 10 denotes a mobile station (MS) which establishes a communication connection for which the subscriber is to be charged. Reference sign 20 denotes a core network element, such as a General Packet Radio Service Gateway Support Node (GGSN), which comprises a PCC portion 25 and to which the MS 10 is connected. Reference sign 30 denotes a PPS (located, for example, in a Home AAA (HAAA) server of the MS 10) which communicates with the PPC portion 25 in the GGSN 20.
According to the basic configuration of DCCA, the PPC is designed to be co-located with anchor point, such as the GGSN 20 in FIG. 9. Thus, when a subscriber's MS 10 moves or is switched to another network access within the network, the anchor point, such as GGSN 20, does not change. In other words, the PPC is not effected by the mobility of the MS 10 and is therefore not changed. Hence, there is no need to consider any mobility issue with regard to the PPC and its location.
However, in so-called flat network hierarchies where the number of network elements involved in a communication connection becomes less, functionalities located in elements of a higher hierarchical order in other networks are moved to network elements of a lower hierarchical order. For example, specific (online) charging functionalities of a PPC may be moved to elements of the access network level, such as to an Access Service Network Gateway (ASN GW) in case of a WiMAX based system.
This means that such functionalities may not be remained in an anchor point in case the MS 10 is moving. Therefore, it is necessary to provide a possibility to relocate the PPC function from one ASN GW/PPC to another ASN GW/PPC. In this case PPC shall be relocated, and charging continuity shall also be guaranteed to support the continuity of subscriber's session. However, this issue is not considered in the original DCCA application.
There have been proposed some approaches to deal with this issue of providing a relocation possibility for the charging client functionality (or part thereof) in case the charging client functionality is located in a network elements affected by the mobility of the MS 10 (i.e. changed, for example, due to a handover from one ASN GW to another ASN GW in a WiMax system.
However, in the proposed mechanisms there may be the following situation. That is, for example, in case of a handover resulting also in relocation of the PPC, a charging agent, such as a prepaid agent (PPA), uses existing quotas (i.e. related to the former or previous PPC). A request for new quotas, directed, for example, to a PPS, is triggered by the PPA when it becomes aware of the PPC relocation completion. However, in such a case, the time necessary for retrieving the new quotas may become too long so that the available (old) quotas may be consumed in the meantime. This may result in a communication connection interruption and the loss of data transmitted via the communication connection.